ABSTRACT
This study included 104 Egyptian infants and children with mental disability and 24 normal children of the same age and sex as a control group. All patients were subjected to full history taking, thorough clinical examination, intelligent quotient [IQ] evaluation and full investigations. The results revealed that 56 of the cases were due to genetic and chromosomal causes [group I], 7 cases were due to prenatal and postnatal insults [group II] and 41 cases were without an exact cause for mental disability [group III]. Complete blood count [CBC], serum iron, iron binding capacity and blood lead levels were compared between group III and the control group. There was no statistically significant difference in serum iron nor blood lead levels between the two groups, while the difference between their serum iron binding capacity was statistically significant. Blood lead levels were significantly positively correlated with ages in group III and the control group and were significantly negatively correlated with the IQ of group III